1. Field of the Invention
The present invention relates to novel surfactants based on poly(alkylene carbonate)s. The surfactants of the present invention are polyether polycarbonate block copolymer nonionic surface active agents comprising a hydrophilic portion comprised of a polymer selected from the group consisting of polyoxyalkylene polyethers, saccharides, polyoxyalkylene saccharides, and a hydrophobic portion comprised of alkylene and carbonate units arranged in alternating or random order. The hydrophobic portions are bonded to the hydrophilic portion at the site of each reactive hydrogen atom to form the surfactants of the present invention.
2. Description of the Prior Art
Prier, U.S. Pat. No. 4,634,743, relates to block copolymers useful in the preparation of polyurethanes. The polyether polycarbonate block copolymer of Prier is comprised of the residue of a hydrocarbon containing three or more functional groups with active hydrogens, an alkylene polyether, polyamine or amide, polyaromatic carbonate, with a polyether polycarbonate having ether units and carbonate units arranged in random order wherein the polyether polycarbonate blocks are bonded to the alkylene polyether, polyamine, polyamide or polyaromatic carbonate. The copolymers of Prier are useful in the preparation of polyurethane plastics.
Prier differs from the present invention because the present invention relates to polyether polycarbonate block copolymers which have surface active properties and which contain ether carbonate units arranged in alternate or random order. Moreover, Prier fails to appreciate the critical role of carbon dioxide in the properties of polycarbonates. The carbon dioxide content of the polycarbonate is determined by reaction conditions chosen and the nature of the catalysts used to initiate the reactions. Prier does not claim both low molecular weight poly(alkylene carbonate)s having a molecular weight of about 300 to 10,000 and a CO.sub.2 content of greater than 30 percent. Rather, Prier forms molecules having a molecular weight range of about 50,000 to 100,000.
Inoue et al, U.S. Pat. No. 3,585,168, discloses a reaction of alkylene oxides, specifically ethylene oxide, propylene oxide or mixtures thereof, with carbon dioxide in the presence of a catalyst to form polycarbonates containing ether linkages. The polycarbonate formed has a molecular weight of from between 10,000 and 200,000 and usually between 20,000 and 50,000.
Inoue et al, differ from the present invention because Inoue et al do not contemplate the use of a polyfunctional initiator such as is used in the present invention. Further, the Inoue composition is not water soluble and has no surface active properties. It is used for molding articles having either a rigid or slight elastic structure. Accordingly, the present invention differs from Inoue et al.
Stevens, U.S. Pat. 3,248,415, relates to a process for the manufacture of high molecular weight polycarbonates from carbon dioxide and 1,2-epoxides such as ethylene oxide and propylene oxide to yield polycarbonates having a molecular weight of from 700 to 5000. Carbon dioxide and an epoxide are polymerized according to Stevens to yield the polycarbonates. The copolymerization occurs by virtue of the presence of a small controlled concentration of an organic compound having at least 2 and usually 2 to 4 active hydrogens such as a polyhydric alcohol or glycol. The copolymerization occurs at elevated temperatures, super atmospheric pressure and preferably under the conditions of base catalysis.
Stevens does not contemplate forming a polyether polycarbonate surface active agent having alternating carbon dioxide and ether linkages in the polycarbonate hydrophobic block nor does he contemplate a polyether polycarbonate block copolymer surfactant. Accordingly, the present invention differs from Stevens.
Dixon, U.S. Pat. No. 4,137,280, discloses endcapping of hydroxyl groups in a poly(alkylene carbonate) to enhance thermal stability. The polycarbonates formed according to Dixon are made by reacting alkylene oxides such as ethylene oxide and propylene oxide with carbon dioxide; no reference is made to making block copolymers. Dixon differs from the present invention because the resulting repeating structure differs greatly from that proposed in the present invention.
Cuscurida et al, U.S. No. Pat. 4,488,982, disclose low foaming nonionic polyether polycarbonate surfactants and functional fluids. The surfactants and functional fluids of Cuscurida are prepared by reacting a monofunctional initiator with an alkylene carbonate or with an alkylene oxide and carbon dioxide to form polyether polycarbonate materials. When surfactants are produced, they exhibit reduced foaming characteristics as compared to other nonionic surfactants. In terms of viscosity, flashpoints and pour points, the polycarbonates of Cuscurida et al are useful as functional fluids.
Reference is made in Cuscurida to Stevens, U.S. Pat. Nos. 3,248,414; 3,248,415; and 3,248,416 to indicate the method whereby the polyether polycarbonate surfactants are formed. The synthesis routes of Stevens only provide low CO.sub.2 content polycarbonates. Thus, the configuration of Cuscurida presumably resembles the configuration of the polyether polycarbonate materials disclosed in Stevens. Further, Cuscurida does not mention either ABA block copolymer structures, nor surfactants terminated by a hydrophile. Accordingly, the materials of Cuscurida are different than the recurring units of the present invention.
Dixon et al, U.S. Pat. Nos. 4,104,264 and 4,066,630, relate to the thermal stability of a polycarbonate which is improved by capping terminal hydroxyl groups with, in the case of the '630 patent, a compound capable of forming a carbon-oxygen bond, and, in the case of the '264 patent, with any compound capable of forming an oxygen-sulfur bond. The polycarbonates are formed from carbon dioxide and an alkylene oxide. There is no initiator such as is present in the instant invention and consequently the molecular weight is very high. In the '264 patent, the disclosed molecular weight of the polycarbonate which is formed is open ended whereas in the '630 patent, the polycarbonates are those having a molecular weight in excess cf 22,000. The polymers are intended for use as resins and molding products. No reference is made to copolymers containing hydrophilic blocks.
The present invention is not concerned with the thermal stability of polycarbonate groups by capping terminal hydroxyl groups. Rather, the present invention is a polyether polycarbonate surface active agent. Accordingly, the present invention differs from the Dixon et al, patents.
Stevens, Great Britain Patent Nos. 828,523; and '524, disclose polycarbonates prepared by heating a mixture of aliphatic or cycloaliphatic 1,2-epoxides, carbon dioxide and an organic compound having two or more hydrogens as the initiator, using an alkaline catalyst, such as potassium carbonate. This route leads to low molecular weight, low CO.sub.2 content polycarbonates. No mention is made of copolymerization to add a hydrophile. These polycarbonates are used to prepare materials useful in insulation and upholsteries. The present invention is not directed to the use of polycarbonates for insulation and upholstery foams. Accordingly, the present invention differs from the Stevens' references.
Stevens, U.S. Pat. No. 2,787,632, discloses linear low molecular weight polycarbonates possessing terminal hydroxyl groups and averaging between 800 and 5000 in molecular weight. Stevens prepares the polycarbonates by conducting ester interchange between a saturated acyclic diol and a diester of carbonic acid. Metallic sodium or other catalysts are used. The reaction temperature is from between 140.degree. to 200.degree.. The polycarbonates so formed can be free flowing liquids, viscous syrups or solids depending upon molecular weight and hydroxyl number. Those skilled in the art recognize that Stevens made a low CO.sub.2 content polycarbonate, although actual CO.sub.2 content was never reported. The present invention produces a relatively high CO.sub.2 content. This results in a substantially different molecule than that disclosed in Stevens. Accordingly, the present invention differs from Stevens.
Rajan, U.S. Pat. 4,456,745, discloses polyurethanes prepared from polycarbonates. The polycarbonates which form the polyurethanes are prepared by heating cyclic carbonates in the presence of cationic initiators such as Lewis acid catalysts. Under reaction conditions, the carbonates form a polycarbonate glycol or diol which, when heated with polyisocyanates, is useful in reaction injection molding applications. Accordingly, the present invention differs from Rajan.
Ammons, U.S. Pat. No. 4,024,113, discloses polycarbonates which are useful for making shock absorbing fluids and laminates in automobile windshields. Ammons differs from the present invention because Ammons excludes ethylene and propylene oxides for use in forming the polycarbonates whereas they are the epoxides of choice of the present invention. Accordingly, the present invention differs from Ammons.
Stevens, Great Britain Patent No. 820,603, discloses heating a cyclic glycol carbonate with a polyhydric alcohol to produce products useful in molding compositions. Accordingly, the compositions are useful as impregnates for woven fabrics and coatings for glass and polyethylenes.
Hostetler et al, U.S. Pat. No. 3,305,605, disclose compositions containing polycarbonate polymers as plasticizers and functional fluids. The polymers of Hostetler are prepared by the polymerization reaction of at least one cyclic carbonate monomer in contact with a catalyst such as an alkali earth metal. No reference is made to block copolymers nor the incorporation of hydrophilic blocks. Accordingly, the present invention differs from Hostetler.
Santangelo et al, U.S. Pat. No. 4,665,136, disclose a class of block copolymers and a process for making them. The process comprises reacting an alkylene oxide with CO.sub.2 in an organic solvent in the presence of an organometallic catalyst to form a poly(alkylene carbonate). A second alkylene oxide is subsequently added without a catalyst. The resulting product is a block copolymer comprising distinct, covalently linked, alkylene carbonate blocks. Santangelo et al differ from the present invention because there is no showing of using the product as a surfactant. Further, as can be seen by examining the structure of Santangelo et al, it is clear that it is not within the molecular weight range of the present invention. Accordingly, the present invention differs from Santangelo et al.
Meyers, U.S. Pat. No. 4,686,276, disclose an improved process for the preparation of poly(alkylene carbonate)s polymers. The process comprises the reaction of alkylene oxide with carbon dioxide and/or an alkylene carbonate at elevated temperature and pressures. The improvement comprises a special catalyst which is an alkaline catalyst and a stannate compound. The process forms only the polycarbonate hydrophobe of the instant invention and the catalyst system is specifically designed to provide a CO.sub.2 content below the range of the instant invention. Accordingly, the present invention differs from Meyers.
Harris et al, U.S. Pat. Nos. 4,686,273 and 4,686,274 disclose a process for modifying by increasing the molecular weight of poly(alkylene carbonate) polyols. The method is a transesterification process whereby the final product does not have ABA or even a (AB)n configuration. Rather, during the process, the order of the hydrophobe and hydrophiles is scrambled. This transesterification results in a random cleavage of the hydrophobe with random insertion of the hydrophile. Although this molecule may be water soluble, it will not function as a surfactant. Accordingly, the present invention differs from Harris.